Road construction.



No. 845,910. PATENTED MAR. 5, 1907. C. P. WALTER.. ROAD CONSTRUCTION.

APPLIGTION FILED 11017.?. 1906.

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i l,ph-mim; mea november 7,1906. serai m3423815 To all whom it may concern,.-

Be it known that I, CHARLES P. WALTER, a citizen of the United States, residing at Harrisburg, in the county of Dauphin and State of Pennsylvania, have invented a new' and useful Road Construction, of Which the following is a specification. l

This invention relates to improvements in the construction of road-beds and foundations for roads, sidewalks, and the like, and has for its principal object to provide a road or foundation Which will be thoroughly \va' terproof both at the top and bottom and in which the bottom portion is Wholly protected from the dampness of the subgrade and from' the effects of frost.

The ordinary method of laying road-beds or foundations of concrete consists `in mixing the broken stone, cement, sand, and the like 'to form the concrete and then shoveling or otherwise conveying the same to the point -Where the road is to be laid, and afterrough leveling offy the concrete is tamped and then rolled. A It is Well known that concrete is allowed to remain undisturbed after mixing it will firmly set and become as hard and impervious as stone; but if disturbed or mixed during the process of setting it will rapidly disintegrate and will never possess the strength and firmness of a concrete mixture Which has been allowed to set Without rolling or tamping. Furthermore, there is often delay in the placing and leveling of the concrete in position to form the road. and the cement will become partly set before the leveling, tamping, and rolling operations. The rolling operation, moreover, will cause the cement or grout to rise to the top of the layer .of .broken stone'as the latter is solidified, and the base of this layer of stone is therefore unprotected and to some extent absorbs the dampness of the .subsoil, so that in case of frost-and ,the consequent expansion and contraction l l-due to varying temperatures the roadbed is soon disintegrated.

In carrying out the present invention these disadvantages are overcome and a thorioughly` moisture-proof road-bed or foundationis made.

In the accompanying drawings, Figure l is a sectional view of a road-bed constructed in accordance with the. invention. Fig. 2 is a similar view `showing the invention as ap- .Nrrisn sfrarn'srn'rn'r r sand, cement, and Water.

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eersteneateries.' A i a road-bed or pavement.

ln carrying out the invention the subsoil is excavated-to the proper depth, and on this is placed a layer of dry grout formed ofmixed cement and sand Without Water'. Gn this dry grout is placed a layer of broken stone, which is leveled off Without rolling or tamping. On the layer of broken stone is then poured a very thin grout made from fine rihis thin grout percolates through the layer of broken stone, a por-tion of this mixture serving to hydrate the cement of the bottom layer of dry grout. This bottom layer of grout thus becomes ce# mented to the layer Vof stone and forms a bottom protective layer, which When set Will be thoroughly Waterproof and Will not be affected by the dampness of the soil on which it rests. sorb some'of the moisture of the soil, and the latter Will become, practically dry 'and will thereafter be protected by the im ervious road-bed. The thin groutiills up t e interstices of -the layer of stone, and during the pouring of this grout a quantity of very fine crushed stone or gravel is added and is carried by thegrout down into the spaces between the pieces of stone, enough of the fine crushed stone or gravel being added to form a level road-bed; but as there is no subsequent tamping or rolling operation the surface of the road will be suiiiciently rough to afford a secure foothold for horses. .As the interstices between the stones are filled the grout will accumulate at the top of the layer- -layer of broken stone, so that the ishing or up er layer may be firmly secured thereto.

I c aim- 1. The herein-described method of manufacturing road-beds, said method consisting in placing a layer of dry grouting material on the ground, then adding a layer of broken The dry grout, furthermore, will abvplied to the construction of a foundation for 5'5 through the layerv of broken stone to ll the interstices of the latter, and to hydrate the layer of dry grouting material.

2. The herein-described method of con- In' testimony that I claim the foregoing as I I 5 my own I have hereto affixed my signature 1 struoting a road-bed, said method consisting in the presence of two witnesses.

in first placing a layer of dry groutng material on the ground, then adding a layer of broken stone, then pouring in a thin watery grout, and at the same time adding finelycrushed stone' or gravel, the dry grouting CHARLES P. WALTER.

Witnesses -JOHN A. MOYER,

DANIEL EMANUEL. 

